U.S. patent application number 14/792635 was filed with the patent office on 2015-10-29 for apparatus and method for eliminating blind spot in an rf antenna array.
The applicant listed for this patent is Ruipeng Li, Zheng Shi. Invention is credited to Ruipeng Li, Zheng Shi.
Application Number | 20150310238 14/792635 |
Document ID | / |
Family ID | 51535791 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150310238 |
Kind Code |
A1 |
Shi; Zheng ; et al. |
October 29, 2015 |
APPARATUS AND METHOD FOR ELIMINATING BLIND SPOT IN AN RF ANTENNA
ARRAY
Abstract
The present invention provides an apparatus and method for
eliminating blind spot of a high frequency RF antenna array,
allowing an RFID tag to be detected when placed anywhere on top of
and within the communication range of the RF antenna array. The RF
antenna array includes a first array of RF antenna placed on a
first surface and a second RF antenna placed on a second surface.
The second RF antenna is located directly below or above the area
encompassing borders of multiple antennas in the first array, but
is not connected to any electrical path. Through the
electromagnetic induction with the EM field generated by the first
RF antenna array, a second EM field is formed by the second RF
antenna, which enables detection and identification of the RFID tag
placed on the blind spot of the first array of RF antenna. The
present invention is useful in improving the RF communication range
and accuracy of a passive RFID system.
Inventors: |
Shi; Zheng; (Beijing,
CN) ; Li; Ruipeng; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shi; Zheng
Li; Ruipeng |
Beijing
Beijing |
|
CN
CN |
|
|
Family ID: |
51535791 |
Appl. No.: |
14/792635 |
Filed: |
July 7, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/CN2014/093763 |
Dec 12, 2014 |
|
|
|
14792635 |
|
|
|
|
PCT/CN2014/080495 |
Jun 13, 2014 |
|
|
|
PCT/CN2014/093763 |
|
|
|
|
PCT/CN2014/079892 |
Jun 13, 2014 |
|
|
|
PCT/CN2014/080495 |
|
|
|
|
PCT/CN2014/072961 |
Mar 6, 2014 |
|
|
|
PCT/CN2014/079892 |
|
|
|
|
PCT/CN2014/071850 |
Jan 30, 2014 |
|
|
|
PCT/CN2014/072961 |
|
|
|
|
Current U.S.
Class: |
340/10.1 |
Current CPC
Class: |
G06K 7/10356 20130101;
G06F 3/0487 20130101; G06F 3/0428 20130101; G06F 3/0421 20130101;
A63F 13/77 20140902; A63F 13/21 20140901; A63F 13/213 20140902;
A63F 13/23 20140902; G06F 3/04162 20190501 |
International
Class: |
G06K 7/10 20060101
G06K007/10 |
Claims
1. A high-frequency RF antenna array for reading a passive RFID tag
throughout the surface area of the array within the communication
range of the antennas and without a blind spot, comprising a first
array of RF antenna placed on a first surface, resulting a blind
spot of the first array at an area encompassing borders of multiple
antennas when detecting an RFID tag placed at a certain distance
from the first surface but within the communication range of the
antennas of the first array, an RFID reader that is connected to
the first array of RF antenna, a second RF antenna that is placed
on a second surface, positioned directly below or above the blind
spot of the first array, wherein the second RF antenna is not
connected to any electrical path.
2. The RF antenna array in claim 1, wherein the first array
consists of four antennas of larger squares in shape resulting a
blind spot of the first array in the area of four adjacent corners,
and wherein the second RF antenna is a smaller square in shape, and
is positioned directly below or above the area of the blind spot of
the first array.
3. The RF antenna array in claim 1, further comprising a processor
operatively linked to the RFID reader, wherein the processor is
configured to determine that the RFID tag has been placed on top of
the second RF antenna upon the RFID tag having been detected by the
antennas related to the blind spot in the first array.
4. The RF antenna array in claim 2, further comprising a processor
operatively linked to the RFID reader, wherein the processor is
configured to determine that the RFID tag has been placed on top of
the second RF antenna upon the RFID tag having been detected by the
four antennas in the first array.
5. A method of creating a high-frequency RF antenna array that is
capable of reading a passive RFID tag throughout the surface area
of the array within the communication range of the antennas and
without a blind spot, comprising placing a first array of
high-frequency RF antenna on a first surface, resulting in a blind
spot at an area encompassing borders of multiple antennas when the
first array of RF antenna detects an RFID tag placed at a certain
distance from the first surface but within the communication range
of the antennas of the first array; connecting the first array to
an RFID reader; placing a second RF antenna on a second surface,
directly below or above the blind spot of the first array, wherein
the second RF antenna is not connected to any electrical path;
detecting an RFID tag placed on top of the blind spot of the first
array, by an RF antenna of the first array that is related to the
blind spot.
6. The method in claim 5, wherein the first array consists of four
antennas of larger squares in shape, and wherein the second RF
antenna is a smaller square in shape, and is positioned directly
below or above the area of four adjacent corners of the first
array.
7. The method in claim 5, further comprising, determining, by a
processor that is operatively linked to the RFID reader, that the
RFID tag has been placed on top of the second RF antenna upon the
RFID tag having been detected by multiple antennas in the first
array related to the blind spot in the first array.
8. The antenna array in claim 6, further comprising, determining,
by a processor that is operatively linked to the RFID reader, that
the RFID tag has been placed on top of the second RF antenna upon
the RFID tag having been detected by the four antennas in the first
array.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation in part of International
Patent Application No. PCT/CN2014/093763, entitled "Apparatus and
Method for Eliminating Blind Spot in An RF Antenna Array", filed on
Dec. 12, 2014, which is a continuation in part of International
Patent Application No. PCT/CN2014/080495, entitled "System and
Method to Recognize an Object's ID, Orientation and Location
Relative to an Interactive Surface", filed on Jun. 23, 2014, which
is a continuation in part of International Patent Application No.
PCT/CN2014/079892, entitled "System and Method for Identifying an
Object's ID and Location Relative to an Interactive Surface", filed
on Jun. 13, 2014, which is a continuation of International Patent
Application No. PCT/CN2014/072961, entitled "System and Method for
Identifying an Object's ID and Location Relative to an Interactive
Board", filed on Mar. 6, 2014, which is a continuation in part to
International Patent Application No. PCT/CN2014/071850, entitled
"System and Method for Identifying an Object's ID and Location
Relative to an Interactive Board", filed on Jan. 30, 2014.
[0002] The entire disclosures of each of the above applications are
incorporated herein by reference.
TECHNICAL FIELD
[0003] The present invention relates to an RF antenna array for
detecting an RFID tag. More specifically, the present invention
relates to eliminating blind spot of a high frequency RF antenna
array, allowing an RFID tag to be detected when placed anywhere on
top of the RF antenna array that is within the communication range
of the RF antenna array.
BACKGROUND
[0004] Radio frequency identification (RFID) technology has been
used in a variety of applications such as tracking, security,
transportation, retailing, industrial, and individual
identification. Data communication via RFID technology may be used
for detecting the presence of an object, identifying the object, or
obtaining data associated with the object. In an RFID system, an
RFID tag is attached to an object and communicates wirelessly with
an RFID reader. The RFID reader typically drives a plurality of RF
antennas to detect and identify RFID tags at different
locations.
[0005] In passive RFID systems, the antenna of the RFID reader
emits RF signals to activate passive RFID tags within a reading
range. Once activated by the RF energy, the passive RFID tags are
configured to transmit a responding signal to the RFID reader. The
RFID tag obtains its energy through electromagnetic induction with
the EM field generated by the RF antenna, and the communication
range of the RFID tag is dependent on the intensity of the EM
field. For an RF antenna in the shape of a square, since the
electromagnetic wave radiates less effectively around its four
corners, the intensity of the EM field is weak around the corners,
and thus the RFID tag will be difficult to be detected and
identified if it is placed in close proximity to any corners of the
RF antenna.
[0006] Therefore, for an RF antenna array with multiple antennas, a
"blind spot" is formed as a result at the area encompassing borders
of multiple RF antennas in the array. The blind spot refers to an
area on the surface of the RF antenna array, where an RFID tag
fails to be detected. At the same time, an RFID tag placed
elsewhere outside the blind spot within the effective communication
range of the RF antenna array is detectable to the antenna array.
Practically, there is usually a distance between the surface where
the RFID tag is placed and the surface of the RF antenna array.
Typically the bigger the distance is, the bigger the blind spot
is.
[0007] The present invention provides to an apparatus and method
for eliminating the blind spot in high frequency (13.56 MHz) RF
antenna arrays.
SUMMARY OF INVENTION
[0008] The present invention provides an apparatus and method for
eliminating the blind spot of a high frequency (13.56 MHz) RF
antenna array, allowing an RFID tag to be detected when placed
anywhere on top of the RF antenna array and within the general
reading range of the antenna array.
[0009] In accordance with one embodiment of the present invention,
the high-frequency RF antenna array includes a first array of RF
antenna placed on a first surface, an RFID reader that is connected
to the first RF antenna array, and a second RF antenna placed on a
second surface. Without the second RF antenna, a blind spot would
have formed at an area encompassing borders of multiple RF antennas
of the first array. The second RF antenna is located directly below
or above the blind spot of the first array, but not connected to
any electrical path. The high-frequency RF antenna array further
includes a processor operatively linked to the RFID reader.
[0010] In accordance with one embodiment of the present invention,
once an RFID tag, of a smaller size than that of the antennas of
the first RF antenna array, is placed on or near the surface area
of the blind spot and yet detected by multiple antennas in the
first RF antenna array that overlap the second RF antenna, the
processor is configured to determine that the RFID tag has been
placed on top of the second RF antenna even though the second RF
antenna is not electrically connected to the RFID reader. This is
in contrast to the situation whereby if the second RF antenna is
removed, the RFID tag placed at the same place will fail to be
detected. Therefore, this high-frequency RF antenna array design is
capable of reading a passive RFID tag throughout the surface area
of the array within the communication range of the antennas without
a blind spot.
[0011] The present invention is useful in improving the RF
communication range and accuracy of a passive RFID system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an exemplary schematic diagram illustrating the
formation of the blind spot in an array of RF antennas in
accordance with one embodiment of the present invention.
[0013] FIG. 2A is an exemplary schematic diagram of a birds-eye
view of the high-frequency RF antenna array for reading a passive
RFID tag in accordance with one embodiment of the present
invention.
[0014] FIG. 2B is an exemplary schematic diagram of a
cross-sectional view of the high-frequency RF antenna array with
each layer separated for the purpose of illustration in accordance
with one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] While the present invention will be described using specific
embodiments, the invention is not limited to these embodiments.
People skilled in the art will recognize that the system and method
of the present invention may be used in many other applications.
The present invention is intended to cover all alternatives,
modifications and equivalents within the spirit and scope of
invention, which is defined by the apprehended claims.
[0016] Furthermore, in the detailed description of the present
invention, specific details are set forth in order to provide a
thorough understanding of the present invention. However, it will
be obvious to one of ordinary skill in the art that the present
invention may be practiced without these specific details. In other
instances, well known methods, procedures, components, and circuits
are not described in details to avoid unnecessarily obscuring a
clear understanding of the present invention.
[0017] The present invention may be better understood and its
numerous objects and advantages will become apparent to those
skilled in the art by reference to the accompanying drawings.
[0018] FIG. 1 is an exemplary schematic diagram illustrating the
formation of the blind spot in an array of RF antennas in
accordance with one embodiment of the present invention. As shown
in FIG. 1, an array of RF antennas 101 is embedded on a surface.
Referring to the four antennas 102, 103, 104, and 105 located at
the top left corner of the array, one can see that these antenna
designs are in the square shape and each are connected to an RF
reader (not shown in FIG. 1). One representative size of the
antenna is 62 mm.times.62 mm, and typically the distance between
two adjacent RF antennas in the array is 2 mm. Once an RFID tag 107
is placed on top of antenna 102, its presence is detected and its
location is identified by the RF antenna array. However, as
explained previously, an RFID tag cannot be detected and identified
by any RF antennas in the array if it is placed in close proximity
to the corners of the RF antennas where the electromagnetic wave is
not radiated effectively. For example, once an RFID tag 108 is
placed at the area 106 encompassing borders of the four corners of
the RF antennas 102, 103, 104, and 105, a blind spot of the antenna
array is formed as a result. Those who are skilled in the art will
recognize that blind spots can also occur in areas encompassing
adjacent borders of multiple RF antennas in arrays of different
arrangements from what is being presented in this figure. For
example, a two dimensional array of RF antennas with each of the
antenna being a hexagon will likely form a blind spot at the area
encompassing the adjacent corners of three antennas. Similarly, if
the antennas of the first array are deployed in a three
dimensional, rather than two dimensional, surface, a blind spot is
likely to form in the space that encompasses the corners of
multiple antennas.
[0019] The present invention provides an apparatus and method for
eliminating the blind spot in the first RF antenna array as
illustrated in FIG. 1.
[0020] FIG. 2A is an exemplary schematic diagram of a birds-eye
view of the high-frequency RF antenna array for reading a passive
RFID tag in accordance with one embodiment of the present
invention. As shown in FIG. 2A, the high-frequency RF antenna array
201 includes a first array of high-frequency RF antenna placed on a
first surface, an RFID reader that is connected to the first RF
antenna array, and a second RF antennas 206 placed on a second
surface. The RF antenna array further includes a processor
operatively linked to the RFID reader (not shown in FIG. 2A).
[0021] The first array consists of at least four RF antennas of
squares in shape, e.g., antennas 202, 203, 204, and 205 located at
the top left corner of the array. If an RFID tag 210 is placed on
the surface area of the antenna array and detected only by antenna
202, the processor is configured to determine that the RFID tag has
been placed on top of the antenna 202. As previously described in
FIG. 1, however, a blind spot of the antenna array is formed as a
result at the area encompassing borders of the four corners of the
four RF antennas 202-205. Once an RFID tag 211 is placed on the
blind spot, it is not detected by any of the four RF antennas
202-205.
[0022] The second RF antennas 206 are also squares in shape placed
on a second surface, with each of them located directly below or
above the area encompassing borders of four adjacent corners of
four RF antennas in the first array. One representative size of the
second RF antenna is 22 mm.times.22 mm, a smaller size relative to
the first RF antenna array. The second RF antenna is not connected
to any network or electrical path in any form. It consists of coils
as well as electronic components such as electric capacitors and
electric resistors. Therefore, an RFID tag cannot be detected by
the second antenna independently because the second antenna is not
operatively linked to the RF reader or the processor. However,
through the electromagnetic induction with the EM field generated
by the first RF antenna array, a second EM field, in an opposite
direction to the EM field generated by the first RF antenna array,
is generated by a second RF antenna. With the formation of the
second EM field, the second RF antenna can reach the optimal
resonance with the first RF antenna array and thus enables the
detection and identification of the RFID tags placed on the second
RF antenna by the RF antennas in the first array. Once an RFID tag
is placed on the surface area of the RF antenna array and detected
by multiple antennas in the first array, the processor is
configured to determine that the RFID tag has been placed on top of
the second RF antenna. Therefore, this high-frequency RF antenna
array is capable of reading a passive RFID tag throughout the
surface area of the array within the communication range of the
antennas without a blind spot.
[0023] For example, if the RFID tag 211 is again placed on the
surface area of the antenna array and detected by all of the four
antennas 202-205, with the existence of a second antenna 206, the
processor is configured to determine that the RFID tag has been
placed on top of the second antenna 206, i.e., the area
encompassing borders of the four adjacent corners of the four RF
antennas 202-205. And this is in contrast to the situation whereby
the RFID tag 211 placed at the same place will fail to be detected,
if the second RF antenna 206 is removed, even though the second RF
antenna 206 does not have electrical connection to the RFID reader.
Those who are skilled in the art will recognize that this
high-frequency RF antenna array is capable of reading a passive
RFID tag throughout the surface area of the array within the
communication range of the antennas without a blind spot.
[0024] FIG. 2B is an exemplary schematic diagram of a
cross-sectional view of the high-frequency RF antenna array with
each layer clearly spread for illustration sake in accordance with
one embodiment of the present invention. Once can see in FIG. 2B
that the bottom layer 207 is the substrate or base of the high
frequency RG antenna array. The first surface 209 embedded with the
first antenna array is placed above the bottom layer 207. In
between the bottom layer 207 and the first surface 209 is the
second surface 208 embedded with second RF antennas 206. Those who
are skilled in the art will realize that the second surface 208 can
also be on top of the first surface 209. Therefore, each of the
second RF antennas 206 is positioned directly below or above a
blind spot of the first array.
* * * * *